Sears Holdings ( SHLD) said Tuesday that Alan Lacy, the former CEO of Sears Roebuck who helped spearhead the retailer's merger with Kmart, will leave the company at the end of the month.

Lacy currently serves as vice chairman of Sears Holdings, which was formed by the Sears and Kmart merger last year. He originally served as CEO of the new company, but was replaced in September by Kmart executive Aylwin Lewis.

Lacy will leave July 29 and will resign from the boards of Sears Holdings and Sears Canada, the company said.

The departure isn't entirely unexpected, as Lacy is set for a big payout by leaving. In a March proxy filing, Sears disclosed that Lacy had options to purchase 200,000 shares that would vest in four annual installments. But the vesting of the options would accelerate if Lacy decided to end his employment in the 30 days after June 30, the proxy said.

Sears Holdings shares closed Tuesday at $156.45 -- significantly above the options' exercise price of $131.11.

"I want to thank Alan for his many contributions to the company," said Sears Holdings Chairman Edward Lampert, the hedge fund guru behind the company's formation, in a statement. "Under Alan's leadership, Sears, Roebuck and Co. took the steps necessary to create a more competitive company. Most importantly, he recognized that the merger of Sears and Kmart would be a powerful opportunity to significantly improve the strategic and financial position of both franchises."